Why do drainage survey bids in Berbera look so low?

Drainage surveys underbidding risks in Berbera start with what the bidder leaves out. A low bid often prices a short site visit and a few spot levels, then stops. It rarely covers a full survey of the site, the runoff estimate, or the route water takes when it leaves the plot. Compare task lists, not totals, and the low bid often stops looking cheap.

What does a low drainage survey bid leave out?

Omitted tasks are the main reason a drainage bid looks cheap. A realistic scope normally includes a site walkover, a level survey tied to a known datum, a check of existing channels and outfalls, a runoff estimate for the design storm, and a drawing that shows flow paths and discharge points. A low bid may price only the walkover and the drawing. Ask each bidder for a method statement that lists every task and the deliverable for each one. If the survey method is not named, the bidder has not priced it.

Why do unrecognized runoff paths break the estimate?

A survey that misses where water goes cannot size the drainage. Water can leave a plot through a neighbour's land, a road gully, a wadi bed or the natural fall of the ground. Each route changes the pipe size, the invert levels and the outlet works. If the surveyor maps only the plot boundary, the design may show water flowing to a point that floods in the Gu or Deyr rains. Walk the plot with each bidder and ask where the water stood last season. Check the local situation with the municipal engineer's office before the tender closes. Ask whether it holds drainage or flood records for the area, and request any survey or outfall information it can share.

How do you find unrealistic tender allowances?

Allowances hidden behind one line item are hard to compare. Ask for a task list with rates for each item: site walkover, level survey, channel survey, runoff calculation, drawing issue, and traffic or access control. Check whether the bid includes depth of cover to the pipe, trench survey points and as-built records. General practice in survey and drainage work is to tie levels to a known datum and record enough points to draw contours, but confirm the required spacing and accuracy against the project specification or engineer. If a bidder cannot explain how the runoff figure was reached or which storm it used, treat that part of the bid as unverified. Ask the bidder to state the storm return period used and where the discharge point is.

What to do next

Before awarding, send one written query to every bidder: list the survey tasks priced, name the design storm and discharge point, and state the datum used. Compare the answers side by side, then walk the plot with the preferred bidder after the next heavy rain. Check what the tender and contract allow before you sign.